A barcode is an optical machine-readable representation of information. Devices for identifying or extracting information from barcodes are generally referred to as barcode readers (or barcode scanners). An image-based barcode reader includes a camera for capturing an image of a barcode to be read. The camera includes a lens that focuses light reflected from a target area onto a photo sensor array. Once an image of a barcode has been captured by the camera, a decoder processes the image and extracts the information contained in the barcode.
Some barcode readers have multiple illumination systems for illuminating the target area. Each illumination system may have different illumination characteristics. For example, a barcode reader may be configured with two different illumination systems: a bright field illumination system and a dark field illumination system. The bright field illumination system may provide illumination having characteristics designed to illuminate a target area that is located relatively far away from the reader. Conversely, the dark field illumination system may provide illumination having characteristics designed to illuminate a target area that is located relatively close to the reader.
One problem that readers with multiple illumination systems have is that it is unknown which illumination system will provide the best illumination for reading a barcode in a particular situation. For example, a reader that has both bright field and dark field illumination may capture an image of a barcode using one of the two illumination systems and attempt to decode the barcode. If the barcode is not successfully decoded, a second image may be captured with the other illumination system, and another attempt may be made to decode the barcode.